GNSS观测的2021年青海玛多地震(Mw 7.4)同震形变及其滑动分布  

Coseismic Deformation and Slip Distribution of 2021 Mw 7.4 Madoi Earthquake from GNSS Observation

作　　者：李志才[1] 丁开华 张鹏[1] 温扬茂[3] 赵利江 陈建峰 LI Zhicai;DING Kaihua;ZHANG Peng;WEN Yangmao;ZHAO Lijiang;CHEN Jianfeng(Geodesy Datum Department,National Geomatics Center of China,Beijing 100830,China;School of Geography and Information Engineering,China University of Geosciences,Wuhan 430074,China;School of Geodesy and Geomatics,Wuhan University,Wuhan 430079,China;Qinghai Institute of Basic Surveying and Mapping,Xining 810001,China;China Mobile Intelligent Mobility Network Co.Ltd,Shanghai 201206,China)

机构地区：[1]国家基础地理信息中心测绘基准部,北京100830 [2]中国地质大学(武汉)地理与信息工程学院,湖北武汉430074 [3]武汉大学测绘学院,湖北武汉430079 [4]青海省基础测绘院,青海西宁810001 [5]中移智行网络科技有限公司,上海201206

出　　处：《武汉大学学报（信息科学版）》2021年第10期1489-1497,共9页Geomatics and Information Science of Wuhan University

基　　金：国家自然科学基金(41774011,41874011,41804038);国家重点研发计划(2016YFB0501405)。

摘　　要：北京时间2020年5月22日2时,中国青海省果洛州玛多县发生Mw 7.4地震。收集震中附近9个连续运行卫星定位基准站(continuously operating reference stations,CORS)观测数据,基于模糊度解算的精密单点定位(precise point positioning with ambiguity resolution,PPP-AR)技术处理了2 h时段的高频(1 Hz采样)全球导航卫星系统(global navigation satellite system,GNSS)数据,快速确定本次地震的近场同震位移,其中水平方向最大约为0.6 m。结合远场12个CORS震前、震后各3 d低频(30 s采样)数据的非差PPP解算同震形变场,基于弹性位错模型反演了玛多地震断层几何参数和滑动分布。结果显示:玛多地震属于典型走滑事件,发震断层走向278.49°,倾角为64.38°,滑动角为-10.90°,破裂长度约为138.72 km,宽度为4.82 km;滑动量超过3 m的滑移主要集中在东部小于18 km深度的区域,最大破裂可达4.2 m。反演的地震矩为1.85×1020Nm,相当于矩震级7.45,比美国地质调查局利用地震波的反演结果略大。Objectives:At 2:00 on May 22,2020(UTC+8),an Mw 7.4 earthquake struck Madoi County,Qinghai Province,China.The earthquake occurred in the unattended area of the Qinghai Tibet Plateau,with less injuries and building damage,but caused obvious surface rupture.Methods:9 high frequency continuously operating reference stations(CORS)data with 1 Hz sampling rate were collected near the epicenter,and the co-seismic deformation was derived from high frequency observation data with 1 hour before and after the earthquake based on precise point positioning with ambiguity resolution(PPP-AR).The low frequency data with 30 s sampling of 12 CORS around Madoi County were collected before and after the earthquake within 3 days to solve for the permeant co-seismic deformation based on the non-differential precise point positioning(PPP).Results:The comparison between these two kinds of co-seismic deformation illustrates that the co-seismic deformation from the high frequency(1 Hz)data is slightly smaller than that of the low frequency(30 s)data.The maximum observed global navigation satellite system(GNSS)co-seismic displacement is about 0.6 m.Further,the fault geometry and slip distribution of the earthquake were inverted based on the permanent co-seismic deformation.Conclusions:The inversion results indicate that the Madoi earthquake is a typical left-lateral strike slip event(rake angle:-10.90°),with a strike of 278.49°and dip angle of 64.380.The rupture length is about 138.72 km.The slip distribution reveals that more than 3 m slip is mainly concentrated in the eastern asperity with the depth of less than 18 km with the maximum slip of 4.2 m.The geodetic seismic moment is about 1.85×1020 Nm,equivalent to Mw 7.45,which is slightly larger than the result of United States Geological Survey(USGS)from seismic waves.

关 键 词：玛多地震 连续运行卫星定位基准站(CORS) 同震形变 断层滑动分布反演 

分 类 号：P227[天文地球—大地测量学与测量工程]